The invention relates to a method for the preparation of oligomcric and/or polymeric radiation-sensitive precursors of polyimides and polyisoindoloquinazoline diones, as well as to the use of these radiation-sensitive precursors.
Soluble radiation-sensitive polyimide and polyisoindoloquinazoline dione precursors are required, for example, in the simple photolithographic production of highly heat-resistant structured protective and insulating layers used in semiconductor engineering. Economical production methods are sought which do not require any expensive purification processes, especially for the removal of chloride.
Polyimide and polyisoindoloquinazoline dione precursors of the type mentioned above, which are soluble in organic solvents, are known for example, from U.S. Pat. No. 3,957,512. These precursors are poly-condensation products of polyfunctional carbocyclic or heterocyclic compounds containing radiation-sensitive radicals, and diamines. The compounds containing radiation-sensitive radicals have two carboxylic acid groups suitable for condensation reactions, and partly in ortho- or peri-position thereto, radiation-sensitive radicals bound to carboxyl groups in ester fashion. The diamines to be reacted with these compounds have at least one cyclic structural element.
Radiation-sensitive polyimide precursors are produced in particular by adding unsaturated alcohols, such as allyl alcohol, to tetracarboxylic acid dianhydrides, such as pyromellitic acid dianhydride; transforming the free carboxylic acid groups of the resulting diesters into acid chloride groups; and subjecting the formed diester-bis-acid chlorides to a poly-condensation reaction with a diamine, which is usually aromatic. With the use of diamino compounds which contain ortho-positioned amido groups, polyisoindoloquinazoline diones are formed analogously.
The known production method, therefore, requires several reaction steps, and also requires that the processes be carried out at low temperatures. Additionally, with the use of acid chlorides intensive purification of the reaction products is necessary.
For the preparation of oligomeric and/or polymeric radiation-sensitive precursors of polyimides and polyisoindoloquinazoline diones a further method is known in which olefinically unsaturated monoepoxides are caused to react with carboxyl group-containing polyaddition products of aromatic and/or heterocyclic tetracarboxylic acid dianhydrides and diamino compounds, or respectively diamino compounds having at least one ortho-positioned amido group (U.S. Pat. No. 4,385,165). Often, however, the reactions do not proceed completely, so that the precursors obtained in this manner may be impaired with respect to their radiation-sensitive nature.